1. Field of the Invention
The present invention relates to a swimming goggle.
2. Discussion of the Background
Conventionally, the goggles of this type have been described in Unexamined Japanese Utility Model Publication No. Hei 1-36505 and U.S. Pat. No. 4,264,987.
The prior art swimming goggle described above includes a pair of right and left eye-cups; a coupling member for coupling the opposed inner end portions of the eye-cups with each other, connecting members connected to the outer end portions of the eye-cups; and an elastic band for joining the outer end portions of the connecting members with each other.
In the above prior art swimming goggle, for holding the water-tightness of the eye-cups to the user's face and for preventing the positional shift of the eye-cups, the length of the elastic band has been adjusted such that the tension of the elastic band is enlarged.
As a result of this adjustment, however, when the tension of the band becomes excessively larger, the eye-cups are deeply forced toward the eyesockets and the vicinities thereof, which causes pain to the user. On the contrary, when the tension is reduced to the extent that the pain is avoided and the water-tightness can be held, there often occurs an inconvenience in that the position of the eye-cups on the user's face is shifted or the eye-cups are reversed due to the external force caused by shock in diving.
Namely, as shown in FIG. 21, when a rubber band 50 is wound around a cylindrical body 51 and both end portions of the rubber band 50 are stretched in the direction of the arrow, a portion A of the rubber band 50 in contact with the cylindrical body 51 is restricted in terms of its extension by the effect of the friction, whereas a portion B not in contact with the cylindrical body 51 is greatly extended.
The same phenomenon as described above is generated in the case where the swimming goggle is attached around the head of the user. Namely, as shown in FIG. 22, at a rear portion A of the head 52, the degree of contact between a band 53 and the head 52 is high, and the extension and contraction of the band 53 is restricted by the friction. On the contrary, at a front portion B of the head 52, the degree of contact between the band 53 and the head 52 is or, in other words, the degree of freedom for the extension and contraction is high, and the extensible portion B is excessively extended by the shock in diving, thereby causing the positional shift and reversing of the eye-cups 54.